Allopatric speciation

	Email		Print
	Bookmark		Link

Allopatric speciation

Allopatric and allopatry are terms from biogeography

Biogeography

Biogeography is the study of the distribution of biodiversity over space and time. It aims to reveal where organisms live, and at what abundance....
, referring to organism

Organism

In biology, an organism is any life thing . In at least some form, all organisms are capable of response to stimulus , reproduction, growth and developmental biology, and maintenance of homeostasis as a stable whole....
s whose ranges are entirely separate, so that they do not occur in any one place together. If these organisms are closely related (e.g. sister species), such a distribution is usually the result of allopatric speciation.

Allopatric speciation, also known as geographic speciation
Speciation

Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages....
, is the phenomenon whereby biological populations are physically isolated by an extrinsic barrier and evolve intrinsic (genetic) reproductive isolation, such that if the barrier breaks down, individuals of the populations can no longer interbreed.

Discussion

Ask a question about 'Allopatric speciation'

Start a new discussion about 'Allopatric speciation'

Answer questions from other users

Full Discussion Forum

Encyclopedia

Allopatric and allopatry are terms from biogeography

Biogeography

Biogeography is the study of the distribution of biodiversity over space and time. It aims to reveal where organisms live, and at what abundance....
, referring to organism

Organism

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring....
arise. (The word is derived from the ancient Greek

Ancient Greek

Ancient Greek is the historical stage in the development of the Greek language spanning across the Archaic Greece , Classical Greece , and Hellenistic civilization periods of ancient Greece and the classical antiquity....
allos, "other" + Greek patra, "fatherland".) By contrast, the frequency of other types of speciation, such as sympatric speciation

Sympatric speciation

Sympatric and sympatry are terms from biogeography, referring to organisms whose ranges overlap or are even identical, so that they occur together at least in some places....
, parapatric speciation

Parapatric speciation

Parapatric and parapatry are terms from biogeography, referring to organisms whose ranges do not significantly overlap but are immediately adjacent to each other; they only occur together in the narrow contact zone, if at all....
, and heteropatric speciation

Heteropatric speciation

Heteropatric and heteropatry are terms from biogeography, referring to organisms whose geographical ranges overlap or are even identical, so that they occur together at least in some places, but which occupy ecological niches distinct enough to prevent frequent hybridization....
, is debated.

Evolution

Evolution

In biology, evolution is change in the heritability trait of a population of organisms from one generation to the next. These changes are caused by a combination of three main processes: variation, reproduction, and selection....
of reproductive isolation is generally thought to be an incidental by-product of genetic divergence of other traits, particularly adaptive changes that evolve through natural selection

Natural selection

Natural selection is the process by which favorable heritable trait become more common in successive generations of a population of Reproduction organisms, and unfavorable heritable traits become less common, due to differential reproduction of genotypes....
in response to different environmental conditions in separate geographic areas. Ernst Mayr, an evolutionary biologist and famous proponent of allopatric speciation, hypothesized that adaptive genetic changes that accumulate between allopatric populations cause negative epistasis

Epistasis

Epistasis is the interaction between genes. Epistasis takes place when the action of one gene is modified by one or several other genes, which are sometimes called modifier genes....
in hybrids, resulting in sterility

Infertility

Infertility primarily refers to the biological inability of a person to contribute to fertilization. Infertility may also refer to the state of a woman who is unable to carry a pregnancy to full term....
or inviability

Viability

Viability means in general "capacity for survival" and is more specifically used to mean a capacity for living, developing, or germinating under favorable conditions....
.

Allopatric speciation may occur when a species is subdivided into two large populations (dichopatric or vicariant speciation) for example by plate tectonic or other geological events, or when a small number of individuals colonize a novel habitat on the periphery of a species' geographic range (peripatric speciation

Peripatric speciation

Peripatric and peripatry are terms from biogeography, referring to organisms whose ranges are closely adjacent but do not overlap, being separated by a natural barrier where these organisms do not occur – for example a wide river or a mountain range....
). Because natural selection is a powerful evolutionary force in large populations, adaptive evolution likely causes the genetic changes that results in reproductive isolation

Reproductive isolation

An important concept in evolutionary biology, reproductive isolation is a category of mechanisms that prevent two or more populations from exchanging genes....
in vicariant speciation. In peripatric speciation, however, the genetic changes that are thought to occur within the peripheral isolate are more controversial.

Proponents of peripatric speciation contend that small population size

Small population size

Populations with small population size behave differently from larger populations. Often this has various harmful consequences for the survival of that population....
in the peripheral isolate (sometimes referred to as a "splinter population") allows genetic drift

Genetic drift

Genetic drift or allelic drift is the change in the relative frequency with which a gene variant occurs in a population that results from the fact that alleles in offspring are a Sampling of those in the parents, and because of the role of chance in determining whether a given individual survives and reproduces....
, which can be a more powerful force than natural selection in small populations, to deconstruct complex genotypes, allowing the creation of novel gene

Gene

A gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cell and pass genetic trait to offspring....
combinations. Both forms need not be mutually exclusive; in practice, passive isolation or fragmentation as well as active dispersal seem to play a role in many cases of speciation.

A famous example of allopatric speciation is that of Charles Darwin

Charles Darwin

Charles Robert Darwin Royal Society was an English people natural history who realised and presented compelling evidence that all species of life have evolution over time from common descent, through the process he called natural selection....
's Galápagos Finches

Darwin's finches

Darwin's finches are 13 or 14 separate combinatory species of Passerine birds related to a group that Charles Darwin collected on the Gal?pagos Islands during Second voyage of HMS Beagle....
. Another involves the Asian Elephant

Asian Elephant

The Asian or Asiatic Elephant , sometimes known by the name of one of its subspecies – the Indian Elephant, is one of the three living species of elephant, and the only living species of the genus Elephas....
.